Circuit interrupter



June 16, 1936.

K. WULSTEN CIRCUIT INTERRUPTER Filed Feb. 23, 1934 2 Sheets-Sheet 1 llll INVENTOR hurf Wu/sfen BY ATTORN WITNESSESZ.

June 16, 1936. K, w s 2,044,142

CIRCUIT INTERRUPTER Filed Feb. 25, 1934 2 Sheets-Sheet 2 WITNESSES: INVENTOR zZZ I Kurf Wu/s fer;

QM pM G- \W- /o ATTORNEY Patented June 16, 1936 Kurt Wulsten, Berlin-Charlottenburg, Germany,

assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation .of Pennsylvania Application February 23, 1934, Serial No. 712,535 In Germany February 25, 1933 '7 Claims.

My invention relates generally to moderate power circuit breakers of the type used for controlling lighting and distribution feeder circuits and relates particularly to the closures and arc extinguishing devices which are used therewith.

Circuit breakers of this type present a rather complex problem to the electrical art. Because of the fact that they are very frequently used in dwelling houses and factories, the operation of the breakers must be very reliable and very safe. Further, the breaker and its closure must present an attractive appearance to the architect or prospective purchaser and, in addition, the appearance of the closure must not be marred or other-- wise altered during the operation of the breaker. As against these requirements, the cost of the device must not be excessive, since the breakers compete directly with the older arrangement of a fuse and a separate switch.

In an efiort to reduce the cost of these breakers and to improve their external appearance, it has become general practice in the art to utilize a closure for the breaker which is formed of molded insulating material. In some forms, this closure has arcing chambers molded integral therewith, and in others it includes a supplemental arcing chamber adapted to enclose the individual arc extinguishing devices associated with each pair of moving contacts.

To produce an attractive external finish on the breaker closure, it is practically necessary to use insulating material which comprises, an organic fibre base such as pulp and a binder similar to the phenoliccondensate resins or the urea readily molded into intricate forms through the application of heat and pressure, and the resulting product has a high gloss and presents a very attractive appearance.

Unfortunately, however, the insulating material produced by this process is not are resistant, and if even a moderately thin section is exposed to an electric are on one side, the other side will blister or buckle so as to completely destroy the previous attractive appearance of that side. Thus, while the process yields a comparatively inexpensive closure which is at tractive in appearance and which is comparatively inexpenresult during the operation of the breaker.

The principal object of my invention, therefore, is to provide means whereby an insulating material of the type discussed above may be used for enclosing the portions of a circuit breaker are provided with means of resins. This type of insulating material may be "slve, its use is not entirely satisfactory because of the possible injury to the closure which may or other electrical apparatus which may be exposed to the action of an electrical arc, and I prefer to accomplish this object by molding suitable are resistant inserts into those portions of the arc passage or chamber which may come into 5 contact with the arc during the extinguishing operation.

These inserts may be formed of various arc, resistant materials such as asbestos, porcelain, or the like, or they may be formed of a molded insulating material which utilizes an inorganic fibre such as asbestos in combination with a binder for holding the fibres together. This last arrangement is a particularly suitable one in that it permits the securing of a bond between the arc resistant and the non-arc resistant portions of the closure which will not be injured by repeated rapid heating and cooling of the are resistant portion.

In the preferred embodiment of my invention, I provide a multi-pole circuit breakerwhich utilizes a separate arc extinguishing device of the so-called arc chute type for each of the several portions and which is-provided with a unitary closure for completely closing the moving parts of the breaker f and the individual arc chutes. Each of the individual arc chutes is formed of molded insulating material of the nonarc resistant type, and those portions of the inner surfaces of each of the arc chutes which may contact the arc during the operation of the device are resistant material positioned so as to prevent injury thereto, because of the heat generated by the arc. The outer closure is provided with means for defining a'plurality of supplementary arc chambers, and each of these is lined at those portions which may come into contact with the heated are products with inserts of arc resisting material for preventing damage to the surface and finish of the closure proper.

In another embodiment of my invention, I dispense with the individual arc chutes and draw the are within suitable arc passages or chambers dition, the physical dimensions of the breaker are reduced to a minimum. This reduction is made possible by virtue of the fact that the walls of a closure made in accordance with my inven tion may be brought much closer to the arc without danger of injury due to the heat of the arc than has heretofore been considered possible.

An ancillary object of my invention. which will be brought out somewhat more clearly in the following description of one of the preferred embodiments of my invention, is the provision of an improved arc chute which is less expensive to manufacture than the previously known devices, which maintains its original good appearance throughout its entire life, and which is capable of functioning more satisfactorily than the previously known devices.

Referring to the drawings,

Figure 1 is a side elevational view, partially in section, of a two pole circuit breaker employing the principal features of my invention.

Fig. 2 is a front elevational view, partially in section, of the circuit breaker shown in Fig. 1.

Fig. 3 is a detail plan view of one of the arc chutes used in the circuit breaker shown in Figs. 1 and 2.

Fig. 4 is a sectional view on the line IV-IV of Fig. 3.

Fig. 5 is a side elevational view of the arc chute shown in Fig. 3.

Fig. 6 is an enlarged sectional view on the line VIVI of Fig. 5.

Fig. 7 is a sectional view on the line VII-VII of Fig. 2.

Fig. 8 is an elevational view, partially in section, of a, modified form of closure for the circuit breaker shown in Figs. 1 and 2.

Fig. 9 is a sectional view on the line IXIX of Fig. '8, and

Fig. 10 is a sectional view on the line X--X of Fig. 8.

- Referring particularly to Figs. 1 and 2, the

- circuit breaker comprises a base I, preferably of molded insulating material, upon which is -mounted a pair of terminals 3, a pair of stationary contact members 5, a pair .of movable contact members I, an actuating mechanism 9 for moving the movable contacts I to the open and to the closed circuit position, a pair of are extinguishing devices I I, each of which is adapted to be supported upon a U-shaped pole piece I3, a pair of blow-in coils I 5 for energizing each of the U-shaped pole pieces I3, 2. second pair of terminals l1, and a suitable means I9 for connecting each of those terminals with the lower terminal 2| of the associated blow-in coils. The actuating mechanism 9 is not an important part of my invention, and any of the arrangements which are well known to the art may be utilized. A cover 23 of molded insu ating material cooperates with the base I so as to completely enclose all of the moving parts of the breaker. Two suitably proportioned chambers 25 are molded integral with the cover 23 for enclosing the individual arc chutes II, and the inner surfaces of each of these chambers are provided with suitable inserts 21 of are resistant material for preventing injury to the cover proper by virtue of the heat produced by the arc.

,The electrical circuit through the breaker is comparatively direct and is the same for each of the. two poles. Beginning with the upper terminal 3, the current flows successively through the stationary contact 5, the movable contact I and its supporting shunt 29 to the upper terminal 3| of the associated blow-in coil I5, and thence through that coil to the other terminal of the breaker I1. If desired, a suitable means may be electrically connected between the lower terminal 2! of the blow-in coil I5 and the lower terminal I! of the breaker for causing the opening of the circuit upon the occurrence of overload conditions.

In Figs. 2 and 7, one of the arc chutes II has been removed from the breaker in order to show how those chutes are supported upon the outstanding portions 33 of the pole piece I3 which project through suitable holes 35 in the base I of the breaker. The are chutes II are formed from two substantially symmetrical half sections 3'! as is shown particularly in Figs. 3, 4, and 6. Each of these sections 31 is provided with a portion 39 adapted to overlappingly engage a similar cooperating portion 39 formed integral with the other half section. This is shown particularly in Figs. 4 and 6. By this arrangement, the cooperating half sections 31, when assembled, engage each other with a substantially gas-tight joint, thereby causing all of the are products to be vented through the vent openings 4| and 43 provided in the corners of the chutes themselves.

As shown, the arc chutes II are rectangular in shape, this arrangement being particularly satisfactory for use in applications where the available space is a minimum. Each of the half sections 31 is provided with a recess 45 molded integral therewith for engaging one of the opposed sides 33 of the pole pieces I3 of the blow-in magnet. These side portions 33 of the pole pieces are formed of comparatively heavy material, and when the arc chutes II are placed in position in the assembled breaker, the two half sections 31 are securely held together against any internal pressure that may be developed within the device during the operation of the device. No

means other than the side portions of the pole lating material which comprises an organic fibrous base and a resinous binder. While. the resulting product is not arc resistant, it presents an excellent appearance, and if, as is done in the structure shown in the drawings, inserts of an are resistant insulating material are molded into the inner walls of the device, there is no possibility of the non-arc resistant portion of the extinguishers being injured during the arc extinguishing operation. Another advantage of this form of molded insulating material is its physical strength, which is much greater than the materials heretofore used. This permits further reduction in the size of an arc extinguisher, wherein it is used, because thereis no danger of the extinguisher being injured by the large mechanical forces sometimes developed during arc extinction.

The location of the narrow slot vents 4| and 43 in the corners of the arc extinguishing device II of my invention is of particular value in preventing the cover 23 of the breaker from being exposed to the direct flame of the arc, since the outwardly flowing gases are caused to r 1 2,044,142 follow a circuitous passage in venting into the supplemental arc chambers 25. This feature of circuitous venting, which is in part made possible by the gas-tight joint resulting from the overlapping engaging portions 39 of the arcextinguishers, in combination with the inserts 21 of are resistant material which are positioned in the adjacent portions of the breaker closure itself, serve to prevent any possible injury to the cover by the heat of the arc.

If a cover of the type shown in Figs. 8, 9, and 10 is utilized, it may be possible to eliminate the arc chutes H entirely. In the arrangement shown, the arc incident to the opening of each pole is drawn within an arc chamber 5| molded integrally with the cover 50 itself. Each, arc

chamber 5| is substantially rectangular in outline and is positioned immediately adjacent the similar chamber for the adjacent pole. A common wall 53 is utilized for separating the two chambers 5|, and in order to prevent any injury to the non-arc resisting portion of the cover, are resistant inserts 55 are molded into those portions of eachof the chambers-which would in the normal operation of the device contact the arc. Thus, the objects of my invention are accomplished in a simple and inexpensive manner.

In order that the appearance of the circuit breaker may be uniform, I prefer to form both the base and the cover of the same type. of molded insulating material. This material, as mentioned above, preferably comprises an organic fibrous base and a resinous binder. The are resistant inserts may be formed of asbestos board, or of a ceramic refractory material, or, if desired, they may be formed of an insulating material which comprises an inorganic fibre base and a resinous binder therefor. This last type is one which I find particularly suitable for accomplishing the objects of my invention, because by a proper selection of the two resinous binders, it is possible'to secure a bond between the arc resistant and the non-arc resistant por tions of the closure, which is not in any way iniured by the repeated rapid heating and cooling incident to the interruption of any arc.

From the above, it will be seen that I have provided means whereby a non-arc resistant insulating material, such as the moldable compounds of an organic fibre and a resinous binder, may be used in the formation of a closure for electrical apparatus without having to consider whether or not an arc may be drawn within the closure during the operation of the device. By virtue of my invention, I am able to considerably decrease the physical dimensions and at the same time eliminate any possible danger of injury to the non-arc resistant portion of the closure because of the heat of the are. -Moreover, the features of my invention permit the securing of an increased margin of safety to apparatus wherein they are incorporated, be-

cause of the fact that the insulating material which is used for the closure may be selected not on the basis of its arc resisting qualities but on the basis of its mechanical strength and good appearance.

In addition to the above, I have disclosed the features of an improved closure for a multi-pole circuit interrupter or like device which permits the utilization of a non-arc resistant material for the outer surface thereof, in order that a desirable appearance may be achieved, and which at the same time is provided with are passages molded integral therewith, this improved closure being provided with means for preventing injury to the appearance of the non-arc resisting-portion thereof by the heat of the arcs which are established in the arc passages'during the operation of the device. 5

I have also shown an improved form of arc chute which is readily assemblable to form an arc-- extinguishing device wherein the outward flow ofthe are products is carefully controlled, and which may safely be formed of non-arc resist- 10 ing insulating material without anydanger of that material being injured by virtue of the heat of the arc.

In accordance with the patent statutes, I have disclosed the details of a preferred embodiment 15 of my invention. Most of these details are, 'however, merely illustrative, and it is my desire that the accompanying claims shall be accorded the broadest reasonable construction and shall be limited only by what is explicitly stated therein 20 and by the prior art.

I claim as my invention:

1. In electrical apparatus, means for establishing an arc, and means for extinguishing said are comprising an arc chamber which is substantially 26 rectangular in outline and within which said are is established by said arc establishing means, the walls of said are chamber being formed by the assembling of two substantially symmetrical half sections, each of said half sections having a por- 30 tion adapted to overlappingly engage a similar portion formed integral with the other section so as to form a substantially gas-tight joint, and including vent means comprising narrow slots disposed adjacent the corners thereof so as to 3 be spaced some distance from said joint.

2. In a device for extinguishing electrical arcs,

means of insulating material for defining an arcing chamber which is open on not more than one of its sides, said means including two sub- 40 stantially symmetrical half sections of molded insulating material, each of which has a portion adapted to overlappingly engage the cooperating section so as to form a substantially gas tight joint and has means of arc-resistant insulating 45 material molded into the walls thereof for protecting at least a portion of the inner surface of each of said sections from the heat of the arc, and means for defining vents in said arcing chamber, said vents being spaced some distance 50 from. said gas tight joints.

3. In a device for extinguishing electrical arcs, means of insulating material for defining an arcing chamber which is substantially rectangular in outline and which is closed on its top, bottom, 55 and at least three sides, said means including two substantially symmetrical half sections of molded insulating material, each of which has a portion adapted to overlappingly engage a similar portion formed integral withthe othersection so 60 as to form a substantially gas tight joint and has means of are resistant insulating material molded into the walls thereof for protecting at least a portion of the inner surface of each of said sections from the heat of the arc, and means for 5 defining vent slots in said arcing chamber, said 5 having a portion adapted to overlappingly engage a similar portion formed integral with the other section so as to form a substantially gas-tight joint and having means of arc resistant insulating material molded into the walls thereof for protecting at least a portion of the inner surface of each of said sections from the heat of the arc, and means for defining vents in said arcing chamber, said vents being spaced some distance from said gas tight joints.

5. In a device for extinguishing electrical arcs, means of insulating material for defining an arcing chamber which is open on not more than one of its sides, said means including two substantially symmetrical half sections which are molded from an insulating material comprising a fibrous base and a resinous binder, each of said sections having a portion adapted to overlappingly engage a similar portion formed integral with the other section so as to form a substantially gas-tight joint and having means of an insulating material which comprises an inorganic fibre base and a binder molded into at least a portion of the walls thereof, in order to provide are resistant inserts for protecting the inner surfaces of said arc chamber from the heat of the arc, the said resinous binder and the binder used for the said inserts being capable of forming a bond between said walls and said inserts which will withstand 6. In a device for extinguishing electrical arcs,

means for defining the walls of an arcing chamber, including two substantially symmetrical half sections formed of molded insulating material,

each of said sections having a portion which is adapted to overiappingly engage a similar portion formed integral with the other section so as to form a substantially gas-tight joint, and means for defining vents in said arcing chamber, said vents being spaced some distance from said gastight joints.

7. -In a device for extinguishing electrical arcs, means of insulating material for defining the walls of an arcing chamber which is normally open on not more than one of its sides, said meansincluding two substantially symmetrical half sections of molded insulating material, each of which has a portion adapted to overlappingly engage a similar portion formed integral with the other section so as to form a substantially gas-tight joint, and means for defining vent slots in said arcing chamber, said vent slots being spaced some distance from said gas-tight joints.

KURT WULSTEN. 

